Paleoproductivity proxies and alkenone precursors in the Western Mediterranean during the Early-Middle Pleistocene transition

Multidisciplinary analyses (taxonomic analysis of coccolithophore assemblages, stable oxygen isotopes, marine and terrestrial biomarkers) have been carried out on sediments from Ocean Drilling Program Site 975 in the Algero-Balearic basin (38°53.8′ N, 4°30.6′ E), through late marine isotope stage (MIS) 20-19 (from 800 to 756 thousand years ago). The aim of the study was to compare coccolithophore paleoproductivity proxies, such as C37 alkenone concentration (ng/g) and nannofossil accumulation rate (NAR=coccoliths * cm- 2 * kyr-1), and understand their relationship with paleoceanographic condition and paleoenvironmental changes, alkenone-producing precursors and unsaturated C37 alkenone compounds (C37:2, C37:3, C37:4).